The invention relates to an exhaust pipe for a multi-cylinder piston internal-combustion engine having at least one interior pipe carrying the exhaust gases and having a gastight cooled housing which surrounds the interior pipe at a distance, the interior pipe fastened to the surrounding housing comprising individual sections arranged in series while leaving expansion joints, the length of each section corresponding approximately to the cylinder spacing of the piston internal-combustion engine, and each section having a plug-type connection which interacts with the housing at approximately the halfway point of its length, at the outer circumference. An exhaust pipe of that type has a very low surface temperature so that a piston internal-combustion engine equipped with it meets the requirements for an unmonitored operation.
An exhaust gas pipe of this type is known from the German patent document DE 34 45 017 C1. The plug-type connection at the exhaust gas outlet of every cylinder which interacts with the housing has in each case the object of fixing the section of the interior pipe in the longitudinal and in the circumferential direction. The excitation of vibrations of the interior pipe resulting from the pulsating exhaust gas flow cannot be prevented by the known arrangement. The reason is that the plug-type connection has a play between the interior part and the exterior part in all operating conditions, whereby a vibration-reducing support of the sections of the interior pipe becomes impossible.
It is therefore an object of the invention to further develop the exhaust pipe of a multi-cylinder piston internal-combustion engine having an interior pipe carrying the exhaust gases and having a gastight housing surrounding this pipe at a distance so that an excitation of vibrations of the interior part caused by the exhaust gas flow is avoided.
According to the invention, this object is achieved by means of the characterizing part of claim 1 and is further developed by means of the characterizing parts of claims 2 and 3.
An arrangement wherein the plug-type connection is arranged approximately opposite the lead-in point of an exhaust stub of a cylinder interacting with the section, wherein the plug-type connection comprises a receiving device arranged in the housing in a cooled manner and a corresponding plug which is connected with the section of the interior pipe.
In certain preferred embodiments, the receiving device is a flange busing having a bottom which is inserted in a sealing manner into an opening of the cooled interior wall of the housing. In certain preferred embodiments, the plug is fastened in a detachable manner to the section of the interior pipe by means of a screwed connection.
The support of the sections of the interior pipe by means of the plug-type connection approximately perpendicularly to its longitudinal course at the housing is ineffective in the cold condition because a play exists between the receiving device and the plug. This support will start only when, as a result of the thermal expansion difference, the play in the plug-type connection is eliminated. As a result, the sections of the interior pipe are not supported at the housing before an operating temperature is reached at which an excitation of vibrations would be critical. However, during the warm-up phase of the exhaust pipe, the thermal expansion of the sections of the interior pipe is not hindered.
The advantages achieved by means of the invention are that the plug-type connection has a self-adjusting effect; that the plug-type connection of the interior pipe is easy to mount; and that, particularly when the exhaust pipe is arranged with two opposite obliquely entering exhaust gas outlets of cylinders, the excitation of vibrations of the interior pipe is avoided.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.